Improvement



companying drawing,

UNITED STATES PATENT OFFICE.

R. DE WITT BIRCH, OF PHILADELPHIA, PENNSYLVANIA.

Specification forming partei Letters Patent- N0.V11l,305, dated January 3l, 1871.

To all whom it may concern:

Be it known that I, R. DE WITT BIRCH, of the city and county of'Philadelphia, yin the State of Pennsylvania, have invented a neu7 and useful Improvement in the Manufacture of Copperas; l and I do hereby declare the following to lbe a full, clear, and exact description thereof, which will enable others skilled in the art to which it appertains to practice my invention, reference being had to the acwhich forms a part of this specification, and in which;

Figure l is a transverse section of the apparatus which I employ to carry out my invention, taken on the line c y, Fig. 2. Fig. 2 is a longitudinal section of the same, taken on the line 'v w, Fig. l; Fig. 3, a perspective view of the crystallizing-vessel; Fig'. 4, a perspective view of one ofthe crystallizing-sticks; and Fig. 5, a longitudinal section of the blowing apparatus and pipe connected therewitl The same parts are denoted by the same let- .ters in all the figures.

I take the waste liquor from any manufactory where sulphuric acid is employed to act on iron, such as galvanizing works, foundries where castings are cleaned with sulphuric p acid, or other manufaetories, and run this raw liquor into a cistern, where it is allowed to stand for two or three days to deposit impurities, and from which it isv 'pumped into the neutralizing-vessel A. This neutralizing-vessel is lined with lead. Its capacity may be about one thousand five hundred gallons, and it is closed except at'the outlet a. It has also a door, b, through which I throw in enough wrought-iron to neutralize the free acid, and then allow thewholeto stand about four hours, during which it is heated to about S00 Fahrenheit by steam passing through a coil of copper pipe, c, within the neutralizing-vessel. I then run the liquid into the boiler B through the pipe d, (the boiler-end of which is hooked up when not in operation, steam is passed through the copper coil e, and the liquid is thereby boiled down to from 280 to 400 Baume.

The steam and vapors of copperas which escape through the outlets a and b during the operations heretofore described into the chamber C pass over a quantity of common lime in the said chamber, (with which the sulphuric acid unites to form sulphate of lime, depositing metallic iron on the lime,)' and thenceinto the condenser D. By thisv means the greater part of the copperas vapor is intercepted and prevented from passing out into the open air and acting injuriously upon structures and facings of marble or similar stone.

When the liquid has been boiled downto the required density I run it from the boiler into the settling-vessel E by means of the pipe f, which is hooked 'up when not in use, as previously described. After the liquid has stood in the settling-vessel about 4eight hours I run it into the crystallizing-vessel F, elevating the upper end of the pipe g slightly each day, so that it shall always be clear of the previously-deposited sediment.h

The crystallizing-vessel may be lined either with lead or with a composition of one part Trinidad pitch, three parts resin, two parts sulphur, and onepart iron-dust;

Frames or slats h h are wedged or otherwise securely adjusted in the vessel F, so a-s to be just on the top of the liquid. The.ob-

ject of these frames is to keep the crystallizing-sticks (which are thrust between the slats, as shown 1n Fig. 3) immovable and prevent them from floating on the liquid.

I prefer to make the erystallizing-sticks of white l oak. In shape they are octagonal prisms, which. form I have found by experience to be the Vbest adapted to the formation of the crystals on them.

When the crystallizing sticks have been about six days in the crystallizer I remove them and lknock off the crystals of copperas, which are afterward washed in the usual manner, and then laid on the ioor to be dried by the f'ollowin g means: Within the condenser l) is a pipe, G, communicating with the open air, and also with the blowing-machine H, by which a stream of air is forced through .the orilice I. The cold air which enters this pipe is heated by the steam' that escapes from the vessel A and boiler B into the condenser, so that while the steanris condensed and the copperas-vapor prevented, as previously described, from escaping` inany considerable quantity, a current of warm airis continually issuing from the orifice I, in front of which the crystals are laid, and are thereby dried quickly.

An outlet, K, is provided for the escape ot uncondensed steam and vapor.4 The quantity essary to complete the neutralizing process before boiling, thereby incurring loss of time, or

to perform both operations at once, in which case a large quantity of water will be driven oi'before the acid is neutralized, the resulting crystals will contain sulphuric acid, and

vthe vessel and pipes will be coated with a hard deposit, dilli'cnlt of removal.

WhatI claim as my invention, and desire to secure by Letters 'Patent of the United States, is-

1.' The manufacture of' copperas from waste liquor bythe process described.

2.. The process of neutralizing the 'i ree acid in. a separate vessel from that in which the liquid is boiled to the required density.

3. The process of neutralizing, boi-ling,vand' settling the liquid in separate vessels, as described.

4. The above-described method of prevent ing the escape 'of copperas-vapor into the atmosphere.

5. The application of the vapor from the heated liquid to heat the drying-blast, as (lescribed.

6. The combination of the chamber C and condenser D with the pipe G' and blowing- 7. The frames or slats `h h, arranged in the crystallizing vessel, and operating as described.

8. 'llie crystallizing-sticks', made `in the shape and for lthe purpose described.

R, DE WITT BIRCH.

Witnesses;

- WM. R. WRIGHT, THos. A.BURTT. 

